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Discussion Starter · #1 ·
I usually have had excellent success with a SWC style 125 gr bullet from Mountain Moulds using 5 grains of Silhouette powder;. recently I have been testing a 135 grain projectile of a very similar design, same lead mixture, and powder, first impressions were were favourable as the round appeared to be just as accurate as my first choice, but yesterday I found several rounds keyholing. Since the only major difference is the 10 grains in weight I am somewhat puzzled.. The bullet is sized exactly the same as the 125 grain bullet looks good as the 125 grain projectile, cast weight is consistent, the firearms used are the same.. Anyone have any suggestions, I would appreciate it. Both bullets were sized .356 I have loaded a few test rounds sizing them at .358 That I hope to test in a few days, hoping that will change things. As previously mentioned the 125 grain round performs well as can be seen the attached image of 10 rounds fired at 25 meters. I was hoping the new 135 grain would be close!
 

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The Shadow (Moderator)
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Per Ramshot data, 5 grains is almost a max load for a jacketed 135gr bullet. My guess would be you're stripping it from to much velocity/pressure.

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Discussion Starter · #3 ·
That was my first thought, so I tried a reduced load it actually made things worse. Perhaps I will try the same reduced load with the bullet sized at .358. Thanks for your thoughts!
 

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Twist rate might not be quite right for the heavier bullet. Is the heavier bullet manufactured by the same company as the lighter one? Bullet alloy might be different and/or not the same throughout the lot of bullets. Cast bullets can vary a lot because of a number of factors. It doesn’t take much to lose accuracy, even very small differences can produce significantly different results.
 

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What is the twist rate of the barrel from which your fire the 2 weights of projectiles, and what are the projectiles' respective lengths? Can you chronograph your reloads? Are their any obvious defects or differences between the 125s and 135gr. cast projectiles? Some defect in the mold could be imparted to the finished projectile (hollows in bullet interior?). It could be that you are right on the verge of instability with the 125s, but velocity is high enough to just do the job. It could be that the 135 is leaving the barrel just slowly enough that it doesn't have quite the gyroscopic stability necessary to stay "nose on" after launch.
 

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Discussion Starter · #6 ·
The alloy is identical, cast at the same time as the 1st 125 grain, no noticeable defects. The firearm in question seems to handle all weights of jacketed bullets without so much as a hiccup. If I am correct the twist rate is 1-10 It is a SIG p210 Super Target, similar results from my SiG P226 X6
 

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Discussion Starter · #7 ·
What is the twist rate of the barrel from which your fire the 2 weights of projectiles, and what are the projectiles' respective lengths? Can you chronograph your reloads? Are their any obvious defects or differences between the 125s and 135gr. cast projectiles? Some defect in the mold could be imparted to the finished projectile (hollows in bullet interior?). It could be that you are right on the verge of instability with the 125s, but velocity is high enough to just do the job. It could be that the 135 is leaving the barrel just slowly enough that it doesn't have quite the gyroscopic stability necessary to stay "nose on" after launch.
The twist rate is 1-10. Moulds are manufactured by the same manufacturer, Chronograph not working right now :(. Alloy is identical as they were both cast from the same batch I hope to test a few theories later today. cast.jpg
cast.jpg
 

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The Hog Whisperer (Administrator)
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Find a jacketed bullet of the same length, or perhaps a touch longer if possible. If that doesn't keyhole, then twist rate isn't your problem. But, trying to 'twist' a cast bullet too fast under acceleration might be, hmmm.....

Any way to recover a fired bullet? That will tell you if it is stripping the rifling.

Could just be one of those weird things where a cast bullet just doesn't behave with one powder, but may with another. Kind of mysterious and sometimes frustrating, but sometimes that is the world of cast bullets. Did you slug the barrel by chance?
 

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Give the .357" or .358" sized bullets a try ... if that doesn't work ... My Dad would tell me ...
... " Why Boy ...You ain't holding your mouth right ! " .... and He thought that was so funny

You never know what a cast bullet design will do untill you shoot them ... they seem to have a mind of their own .
Gary
 

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Give the .357" or .358" sized bullets a try ... if that doesn't work ... My Dad would tell me ...
... " Why Boy ...You ain't holding your mouth right ! " .... and He thought that was so funny

You never know what a cast bullet design will do untill you shoot them ... they seem to have a mind of their own .
Gary
"Your not holding your mouth right". I still hear that. I've got a Taurus 605 2" stainless, that shoots anything I want to load and shoot in it. Except Hornady swaged 158 gr. SWC. They shoot great in a longer barrel though.
 

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IF the loading data says you have room to bump the powder charge, and IF you feel comfortable with doing so, I would try that.
 

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What is the seating depth difference between the two bullets? What is the relationship of the forward driving band and the case mouth? Is it possible some damage to the driving band of the longer bullet happens when hitting the feed ramp? Have you tried feeding some directly into the chamber by hand instead of through the magazine to see if they perform differently?
 

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If severe lead deposits destabilize a 135 gr. projectile, wouldn't they destabilize the 125s? Maybe it's a threshold thing, where "just enough" of every confound present may be enough in combination to make the 135s tumble. A little bit of barrel cleaning is almost NEVER a bad idea, I guess...
 

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The Shadow (Moderator)
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If severe lead deposits destabilize a 135 gr. projectile, wouldn't they destabilize the 125s?
I never checked Lyman with cast data, but did compare jacketed data. The stated load isn't particularly hot ( jacketed) for a 125gr. But it is almost max for a 135. So the supposition would be the 125's can tolerate the pressure, but it's too high for the 135's and lead deposits can be substantial.

Cheers
 
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The thing that jumps out at me from the photo is how much longer the bearing surface of the 135 looks. This appears to be due to the wide and deep lube grooves. That means the bullet is seating a lot deeper than the 125 is when the same amount of nose is sticking out. That, in turn, can raise peak pressure significantly if you didn't adjust the load way down and start back up. That high pressure, in turn, can cause deformation of the base or stripping of the bullet early in the barrel. Both can cause accuracy issues and tumbling.

Another issue is, at that weight, you could be putting the bullet out of the muzzle right at about the speed of sound, where the initial drag is high. In that situation, it is possible (though not particularly common) for a bullet that would normally be stable to over-correct for initial yaw and start to tumble. Shooting some at about 900 fps or below, where the transonic velocity range isn't a drag issue, would tell you quickly whether that was a factor.
 
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I had another thought . The target ... is it fastened to a backer board , fastened top and bottom ? Or is the target simply clipped / fastened at the top and allowed to dangle .
I have seen targets with no backer board and when fastened at the top ... a bit of wind or breeze can lift the target up ...giving an appearance of a elongated hole .
When shooting / testing make sure the target has a backer board and is taped down at all four corners ... it might not be the bullet or the load or the gun ... it may simply be the target flapping in the breeze .
Gary
 

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Discussion Starter · #18 ·
The thing that jumps out at me from the photo is how much longer the bearing surface of the 135 looks. This appears to be due to the wide and deep lube grooves. That means the bullet is seating a lot deeper than the 125 is when the same amount of nose is sticking out. That, in turn, can raise peak pressure significantly if you didn't adjust the load way down and start back up. That high pressure, in turn, can cause deformation of the base or stripping of the bullet early in the barrel. Both can cause accuracy issues and tumbling.

Another issue is, at that weight, you could be putting the bullet out of the muzzle right at about the speed of sound, where the initial drag is high. In that situation, it is possible (though not particularly common) for a bullet that would normally be stable to over-correct for initial yaw and start to tumble. Shooting some at about 900 fps or below, where the transonic velocity range isn't a drag issue, would tell you quickly whether that was a factor.
Well think you are close, I reduced the power charge substantially and it seems that the problem has somewhat resolved itself, I have yet to do a full and comprehensive test,. but so far it looks promising. I got my hands on a Lab_radar chronograph and was surprised and what velocity the 125 grain SWC were stepping out at. Unfortunately I was unable to check the heavier bullet! When I have the results I will post them
 

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I will admit that over the last 50 + years of handloading and casting bullets , and I reload for a lot of different cartridges ... the 9mm Luger with cast bullets gave me the most trouble .
I din't usually use bad words but there were a couple times when I cursed that round a blue streak ... and swore I was going to toss everything in the river ... but I kept coming back and worked on all the details untill I got it right .
I have never owned a 9mm Luger because I didn't care for the round ... then several years back my Dad gives me a WWII Walther P-38 (my avatar ) he had all these years stashed in his sock drawer and says "here you take this, I don't need it anymore !" Well ...I can't get rid of it and I got to shoot it and I had loading dies...but the 9mm Luger is still a stinker with cast bullets !
Gary
I still don't like 9mm Luger
 

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Discussion Starter · #20 ·
I will admit that over the last 50 + years of handloading and casting bullets , and I reload for a lot of different cartridges ... the 9mm Luger with cast bullets gave me the most trouble .
I din't usually use bad words but there were a couple times when I cursed that round a blue streak ... and swore I was going to toss everything in the river ... but I kept coming back and worked on all the details untill I got it right .
I have never owned a 9mm Luger because I didn't care for the round ... then several years back my Dad gives me a WWII Walther P-38 (my avatar ) he had all these years stashed in his sock drawer and says "here you take this, I don't need it anymore !" Well ...I can't get rid of it and I got to shoot it and I had loading dies...but the 9mm Luger is still a stinker with cast bullets !
Gary
I still don't like 9mm Luger
(9mm I admit is a bit finicky, but truth be told I lucked into a mould that turns out fantastic results on the other hand I have a couple of moulds that are a challenge. I had a P38 that was average and a couple of Lugers that performed quite well. The best 9mm I have had so far is the SIG P226X6 and the SIG P210 as runner-up. All handle my cast 125 grain SWC from Mountian Moulds quite well
 
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